Engine governor bypass system

ABSTRACT

In a vehicle having a power train including an engine and an automatic transmission wherein an engine governor operates to limit maximum vehicle speed there is provided a bypass system which is controlled by the transmission to bypass the engine governor to enable engine speeds in excess of the governed speed to permit transmission shifts that would otherwise not be permitted.

United States Patent 1 Lundbom 1 Feb. 20, 1973 [54] ENGINE GOVERNORBYPASS SYSTEM [75] Inventor: Calvin Lundbom, Southfield,

Mich.

[73] Assignee: General Motors Corporation, De-

troit,Mich.

[22] Filed: Sept. 1, 1971 [21] Appl. No.: 176,861

[52] [1.8. CI. ..74/859, 123/97 R, 123/103 A [51] Int. Cl ..B60k 21/00,F02d 31/00, F02d 1 1/08 [58] Field of Search ..74/856860 [56] ReferencesCited UNITED STATES PATENTS 3/1941 Tibbetts ..74/857 5/1955 Reynoldson....123/103AX 1/1962 Francis ..l23/l03 R UX 4/1966 Smitley et al..74/859 Primary Examiner-Arthur T. McKeon Attorney-J. L. Carpenter eta1.

[5 7] ABSTRACT 4 Claims, 1 Drawing Figure PATENTEUFEBZOIHB 7 1 7', 050

I N VEN TORv ATTORN EY ENGINE GOVERNOR BYPASS SYSTEM This inventionrelates to an engine governor bypass system and more particularly to anengine governor bypass system controlled by an automatic transmission tobypass the normal operation of an engine governor.

In certain engine-automatic transmission-vehicle combinations wherein anengine governor is used to limit vehicle speed, automatic shiftingbetween the transmissions drives is prevented at those throttleconditions where the engine speed required to effect such shifting ishigher than the maximum engine speed permitted by the governor. Forexample, where a full throttle shift point occurs at a speed above themaximum engine speed permitted by the engine governor, the transmissionis prevented from such shift even though the vehicle speed is less thanthe maximum vehicle speed permitted by the engine governor by itscontrol of engine speed.

The engine governor bypass system according to the present invention iscontrolled by an automatic transmission to bypass the engine governor toenable transmission shifting at engine speeds above the normal governedspeed but below that which causes vehicle speed to exceed the limitnormally imposed by the engine governor. The bypass system is operatedby an ignition timing control switch existing in a conventionaltransmission to control the bypass system to bypass the engine governorin the transmissions low speed drives to permit transmission shifting atthose shift point speeds in excess of the maximum engine speed permittedby the governor but at vehicle speeds lower than the limit normallyimposed by the engine governor.

An object of the present invention is to provide a new and improvedengine governor bypass system to permit transmission shifting at enginespeeds which would otherwise not be permitted to occur by an enginegovernor.

Another object is to provide an engine governor bypass system controlledby an automatic transmission to bypass an engine governor to enabletransmission shifting at engine speeds above the normal governed speedwhile not exceeding the vehicle speed limit normally imposed by thegovernor.

Another object is to provide an engine governor bypass system that isoperated by a switch in the transmission whose operation in turn iscontrolled by the transmission drive condition to bypass the enginegovernor to permit transmission shifting at shift points occurring atengine speeds above the normal governed speed while not exceeding thevehicle speed limit normally imposed by the engine governor.

These and other objects of the present invention will be more apparentfrom the following description and drawing in which:

There is shown a vehicle power train with the engine and transmission inelevation, the engine's carburetor and governor in enlarged section anda bypass system according to the present invention in diagrammatic form.

Referring to the drawing, the bypass system according to the presentinvention is shown for use in a vehicular power train comprising anengine which delivers power to an automatic transmission 12 which inturn delivers power via a propshaft assembly 14 and then a differentialto the vehicles driving wheels, the latter two components not beingshown. The engine 10 has a multiple barrel carburetor 16 which iscontrolled by a governor comprising a vacuum motor 18 and a governorvalve 20 which normally operates to limit engine speed and thereby limitmaximum vehicle speed to a predetermined value. Before proceeding to thedetailed description of the engine governor bypass system which isgenerally designated as 22, the details and operation of the carburetor,engine governor and transmission will be described.

The carburetor 16 is of the four barrel type with an air intake 24having two primary barrels 26 of which only one is shown and twosecondary barrels 28 of which only one is shown. Each primary barrel 26is provided with a venturi throat 29 and a primary throttle valve 30downstream thereof. Valve 30 is mounted on a shaft 31 that extendsthrough the other primary barrel, not shown, in which is mounted on thisshaft a throttle valve identical to throttle valve 30. The operatorcontrols the primary throttle valves by linkage, not shown, connected tothe left end of the primary throttle shaft 31. Each secondary barrel 28is also provided with a venturi throat 32 and a secondary throttle valve34 downstream thereof. Valve 34 is mounted on a shaft 36 that extendsthrough the other secondary. barrel in which is mounted on this shaftanother throttle valve identical to valve 34. A secondary throttle valvevacuum motor, not shown, is connected to operate the secondary throttleshaft 36, this latter device being operated by primary and/or secondaryventuri vacuum to open the secondary throttle valve 34 as such vacuumincreases on increasing primary throttle valve opening.

The vacuum motor 18 is for controlling the throttle valves and ismounted on the carburetors body 38 and comprises a housing 40 having apair of recesses 41 and 42. The recess 42 is covered by a flexiblediaphragm 44 which is secured at its perimeter to the housing 40 by acover plate 46. Plate 46 in cooperation with diaphragm 44 provides achamber 48.

A rod 50 is secured at its lower end to the center of the diaphragm 44,passes through a passage 51 in the housing 40 and has a rightwardlyextending upper end 52 which is pivotally connected to a lever 54. Lever54 is rigidly secured to the right-hand end 56 of the primary throttleshaft 31 which extends into the recess 41. The shaft 31 is mounted atthis end in an antifriction bearing 58 and a spring 59 is disposedbetween this bearing and a washer as shown to provide a seal. A tensionspring 61 attached between a pin 62 on the housing 40 and a pin 63 onlever 54 tends to hold the primary throttle valve 30 in the openposition. A cover plate 64 is secured to the housing 40 to cover therecess 41 to protect the mechanism therein.

An orifice 65 at the primary venturi throat 29 and an orifice 66downstream of the primary throttle valve 30 are connected by passages 68and 70 having flow restrictions 71 and 72, respectively, with a passage74 in housing 40. Passage 74 is connected to a passage 76 in cover plate46 which leads to chamber 48. A passage 78 connecting with passage 74terminates in an opening in the housing 40.

The governor valve 20 is for controlling the throttle valve motor 18 andcomprises a stationary housing 80 which is adapted to be mounted on theengine 10 and rotatably supports a shaft 82. Shaft 82 is driven in anysuitable manner in proportion to engine vehicle speed such as beingconnected to be driven by the distributor shaft, not shown. Mounted forrotation with shaft 82 is a laterally extending valve body 84 having abore 86 in which is located a spring 87 that is attached at one end toan internally threaded member 88 which is keyed in the bore. Therightward end of spring 87 is adjustable axially of the bore 86 byturning of an adjacent screw 89 which engages member 88 and is reachedby removing an access screw plug 90. The other end of spring 87 issecured to a governor weight 91 which is movable axially within achamber 92 against the spring and has at the free end thereof a valveportion 94 adapted to close an orifice 96 when the weight is forcedradially outward due to the rotation of the shaft 82 and valve body 84in accordance with engine speed. The engine speed at which the orifice96 is closed is dependent, of course, upon the adjustment of spring 87and the mass of the governor weight 91.

A vacuum balancing air bleed is provided through the governor valve tochamber 48 of the vacuum motor 18 when the orifice 96 is uncovered. Aconduit 98 connects the air intake 24 of carburetor 16 to the interiorofhousing 80 and a conduit 119 connects the latter to passage 78 in themotor housing 40. When the engine is operating at a speed insufficientto close the orifice 96 of governor valve 20, engine vacuum will drawclean air through the conduit 98 into the housing 80, through theorifice 96 and into the chamber 92, through the bore 86 and an axialpassage 120 in the shaft 82 and thence through the conduit 119 topassage 78. This prevents a vacuum from developing in chamber 48 of themotor 18 so that there is no vacuum motor force tending to close theprimary throttle valves. When the engine reaches governed speed, theorifice 96 is closed and the air bleed through the conduit 119 is cutoff. When this occurs, vacuum is developed in chamber 48 andurg'es thediaphragm 44 downwardly against the force of spring 61 to close theprimary throttle valves to provide govemoring action to limit enginespeed.

The carburetor 16, the vacuum motor 18, and the governor valve 20 thusfar described are conventional and operate to govern the engine speed tolimit the maximum vehicle speed as will be well understood by thoseskilled in this art. Furthermore, the automatic transmission 12 is of aconventional type. For example, the transmission may be like that inU.S. Pat. to

'Winchell et al. No. 3,321,056 which provides three forward drives,namely a low, intermediate and a high speed drive with the high speeddrive being a direct drive. Knowing the vehicle speed limit desired, themaximum engine speed is limited by the governor to that speed in thehighest speed transmission drive which produces the vehicle speed limit.In certain applications with automatic shifting transmissions likeWinchell et al., shifts between low and intermediate drive and fromintermediate to high drive can only occur at an engine speed exceedingthe governed engine speed at certain throttle conditions such as wideopen throttle. This prevention of transmission shifting because of toolow an engine speed to effect the shift thus occurs even though thevehicle speed is below the desired limit.

The engine governor bypass system 22 according to the present inventionbypasses the engine governor except in the transmissions direct driveand comprises a solenoid operated bypass valve 122 which is normallyspring biased to a closed position as shown to block a bypass conduit124 that would otherwise connect the conduit 98 directly to the conduit119 and thus bypass the governor valve 20. The valves solenoid 125 isconnected by a conductor 126 to ground and is connected via a conductor128 and a switch 130 to the vehicles electrical power source which isthe battery 131. The solenoid 125 when energized with switch 130 closedoperates to position valve 122 to open the conduit 124 to bypass thegovernor valve 20 so that the chamber 48 of the engine governor vacuummotor 18 is not evacuated even when governor valve 20 is closed. Thusthe engine may exceed the governed speed regardless of whether governorvalve 20 is closed when the bypass valve 122 is open.

The switch 130 is controlled automatically to permit shifting whichotherwise could not occur but does not enable the vehicle to exceed themaximum speed desired. In transmissions of the type of Winchell et al.,it is current practice to employ a switch referred to as a transmissioncontrolled spark or TCS switch which, as disclosed in U.S. Pat. toTooker et al. No. 3,584,521, is used in an ignition timing control tocontrol engine ignition timing according to the transmission drive thatis in effect. In such installations the TCS switch is closed in the lowand intermediate drives and is open in the high or direct drive.According to the present invention the TCS switch serves as the switch130 with the advantage that this switch then serves a dual purpose. Withthe switch 130 being the TCS switch, the solenoid circuit is closed inthe low and intermediate transmission drive and thus in these drives theconduit 124 is .opened by the bypass valve 122 to bypass the enginegovernor valve 20. Thus, the transmission can shift between low andintermediate and from intermediate to high drive when engine speed isrequired to exceed the normally engine governed speed for such shiftingto occur. In low and intermediate drive the highest engine speedrequired for such shifting does not exceed a speed that would produce avehicle speed in excess of the maximum speed desired and thus thevehicle speed limit is not exceeded even though the engine governor isbypassed. In such an installation and in high drive where the maximumvehicle speed could be exceeded without engine governing the TCS switch130 is open and thus the bypass valve 122 is deenergized to close orblock the bypass so that the governor valve 20 is then effective togovern engine speed.

The above described embodiment is illustrative of the invention whichmay be modified within the scope of the appended claims.

I claim:

1. An engine, a carburetor for inducting air and fuel to said engine, anautomatic shifting transmission powered by said engine and operable toprovide a plurality of different transmission drives, engine governormeans for controlling said carburetor to limit engine speed to apredetermined value, and engine governor bypass means controlled by saidtransmission for bypassing said engine governor means in a low speeddrive to permit engine speed in excess of the governed speed to enableshifting from said low speed drive to another drive at an engine speedin excess of the governed speed.

2. An engine, a carburetor for inducting air and fuel to said engine, anautomatic shifting transmission powered by said engine and operable toprovide a plurality of different transmission drives including a lowspeed drive and a high speed drive, engine governor means forcontrolling said carburetor to limit engine speed to a predeterminedvalue, and engine governor bypass means for bypassing said enginegovernor means to permit engine speed in excess of the governed speed,said engine governor bypass means including a switch having an opencondition and a closed condition and operated by said transmission to bein one condition in said low speed drive and in the other condition insaid high speed drive to control said engine governor bypass means tobypass said engine governor means to permit engine speed in excess ofthe governed speed in said low speed drive to enable shifting from saidlow speed drive to said high speed drive at an engine speed in excess ofthe governed speed.

3. An engine, a carburetor including a throttle valve for inducting airand fuel to said engine, an engine governor system comprising a throttlevalve control motor connected to operate said throttle valve and agovernor valve connected to be controlled by engine speed and connectedto control said motor to operate said throttle valve to limit enginespeed to a predetermined value, an automatic shifting transmissionpowered by said engine and operable to provide a plurality of differenttransmission drives including a low speed drive and a high speed drive,and engine governor bypass means comprising a bypass valve operable in abypass condition to bypass said governor valve so that said throttlevalve control motor is not effective to limit engine speed and operablein a non-bypass condition to permit said governor valve to control saidthrottle valve control motor, biasing means for biasing said bypassvalve to said non-bypass condition, an electrical circuit having asolenoid operable on energization to condition said bypass valve in saidbypass condition,

said circuit including a switch operable when closed to energize saidsolenoid and when open to deenergize said solenoid and being operated bysaid transmission to be in one switch condition in said low speed driveand in the other switch condition in said high speed drive to controlthe energization of said solenoid to condition said bypass valve in saidbypass condition in said low speed drive and in said non-bypasscondition in said high speed drive.

4. An engine, a carburetor including a throttle valve for inducting airand fuel to said engine, an engine governor system comprising a throttlevalve control motor connected to operate said throttle valve and agovernor valve connected to be controlled by engine speed and connectedto control said motor to operate said throttle valve to limit enginespeed to a predetermined value, an automatic shifting transmissionpowered by said engine and operable to provide a plurality of differenttransmission drives including a low speed drive and a high speed drive,and engine governor bypass means comprising a bypass valve operable inan open condition to bypass said governor valve so thatsaid throttlevalve control motor is not effective to limit engine speed and in aclosed condition to permit said governor valve to control said throttlevalve control motor, biasing means for biasing said bypass valve to saidclosed condition, and an electrical circuit h avmg a solenoid operableon energization to condition said bypass valve in said open condition,said circuit including a switch operable when closed to energize saidsolenoid and when open to deenergize said solenoid and being operated bysaid transmission to be in said closed switch condition in said lowspeed drive and in said open switch condition in said high speed driveto thereby control the energization of said solenoid to condition saidbypass valve in said open valve condition in said low speed drive and insaid closed valve condition in said high speed drive.

1. An engine, a carburetor for inducting air and fuel to said engine, anautomatic shifting transmission powered by said engine and operable toprovide a plurality of different transmission drives, engine governormeans for controlling said carburetor to limit engine speed to apredetermined value, and engine governor bypass means controlled by saidtransmission for bypassing said engine governor means in a low speeddrive to permit engine speed in excess of the governed speed to enableshifting from said low speed drive to another drive at an engine speedin excess of the governed speed.
 1. An engine, a carburetor forinducting air and fuel to said engine, an automatic shiftingtransmission powered by said engine and operable to provide a pluralityof different transmission drives, engine governor means for controllingsaid carburetor to limit engine speed to a predetermined value, andengine governor bypass means controlled by said transmission forbypassing said engine governor means in a low speed drive to permitengine speed in excess of the governed speed to enable shifting fromsaid low speed drive to another drive at an engine speed in excess ofthe governed speed.
 2. An engine, a carburetor for inducting air andfuel to said engine, an automatic shifting transmission powered by saidengine and operable to provide a plurality of different transmissiondrives including a low speed drive and a high speed drive, enginegovernor means for controlling said carburetor to limit engine speed toa predetermined value, and engine governor bypass means for bypassingsaid engine governor means to permit engine speed in excess of thegoverned speed, said engine governor bypass means including a switchhaving an open condition and a closed condition and operated by saidtransmission to be in one condition in said low speed drive and in theother condition in said high speed drive to control said engine governorbypass means to bypass said engine governor means to permit engine speedin excess of the governed speed in said low speed drive to enableshifting from said low speed drive to said high speed drive at an enginespeed in excess of the governed speed.
 3. An engine, a carburetorincluding a throttle valve for inducting air and fuel to said engine, anengine governor system comprising a throttle valve control motorconnected to operate said throttle valve and a governor valve connectedto be controlled by engine speed and connected to control said motor tooperate said throttle valve to limit engine speed to a predeterminedvalue, an automatic shifting transmission powered by said engine andoperable to provide a plurality of different transmission drivesincluding a low speed drive and a high speed drive, and engine governorbypass means comprising a bypass valve operable in a bypass condition tobypass said Governor valve so that said throttle valve control motor isnot effective to limit engine speed and operable in a non-bypasscondition to permit said governor valve to control said throttle valvecontrol motor, biasing means for biasing said bypass valve to saidnon-bypass condition, an electrical circuit having a solenoid operableon energization to condition said bypass valve in said bypass condition,said circuit including a switch operable when closed to energize saidsolenoid and when open to deenergize said solenoid and being operated bysaid transmission to be in one switch condition in said low speed driveand in the other switch condition in said high speed drive to controlthe energization of said solenoid to condition said bypass valve in saidbypass condition in said low speed drive and in said non-bypasscondition in said high speed drive.